But a push by Orleans Parish District Attorney Leon Cannizzaro's office to try Carter as an adult in a 2009 carjacking ran into a legal snafu, court records show, leaving the case in a no-man's-land between criminal and juvenile courts.

And a separate charge against Carter, for allegedly keeping a shank while in jail, brought an acquittal a week before he allegedly unloaded in the party-packed street on Halloween night, killing 25-year-old Albert Glover, injuring seven others and igniting fears of a tourism drought.

Carter had been free since June on $10,000 bond in the shank case. Four months earlier, an appeals court panel upheld a Criminal District Court judge's ruling that tossed out an armed robbery charge in the carjacking, court records show.

As a 16-year-old, Carter and Adonis Dussett, then 15, allegedly robbed a man of his car using a handgun. Carter was deemed incompetent to stand trial in May 2009, and a Juvenile Court judge remanded him to the state Department of Health and Hospitals.

Juvenile Court records are not public, and Criminal District Court records do not indicate why Carter was found incompetent. Five months later, prosecutors won a grand jury indictment in the same case and transferred the case to Criminal District Court. Carter was taken from the state facility to jail in Orleans Parish.

His public defender challenged the transfer, citing a relatively new law that freezes prosecution once a competency or sanity exam has been ordered. Criminal District Judge Lynda Van Davis agreed, but stayed Carter's release from jail pending an appeal.

A week after her ruling, on April 8, 2010, during a "random shakedown" at the jail, Carter, who is 5 feet, 8 inches tall and weighs 125 pounds, admitted he had a shank, and authorities found a three-inch metal rod wrapped in white tape. By then Carter was nearly 18, and the DA's office charged him in Criminal District Court with carrying contraband on state prison grounds, which carries up to a five-year prison term.

According to her May 10, 2010, written decision in the carjacking, Davis was worried about setting Carter free, saying that "keeping the defendant in custody would allow Carter to receive the psychiatric treatment needed to restore his competency."

"Moreover, this court believed that releasing an incompetent defendant charged with armed robbery posed a danger to the community, if a criminal prosecution against the defendant was upheld," she said in her ruling.

But after the appeals court upheld her ruling, last February, Carter was free of the charge, though he remained in jail until posting bond on the shank charge, court records show. The state Supreme Court on Oct. 11 denied a writ from Cannizzaro's office asking it to review Davis' decision.

Just how long he would have remained at a state facility if his case had stayed in Juvenile Court is unclear.

"Usually when kids are waiting for competency to be restored, they're sitting in the juvenile detention center for months in a legal limbo," said Dana Kaplan, executive director of the Juvenile Justice Project of Louisiana.

She said she was unfamiliar with Carter's case.

Had Carter remained there until the court found him competent, Cannizzaro's office could then have transferred the case to Criminal District Court.

"If the law permits them to be tried in adult court, the district attorney believes the criminal court is a more appropriate place for these serious crimes of violence to be tried in," said Cannizzaro spokesman Christopher Bowman.

"We thought it was a good transfer. The district attorney's office feels like it had a good argument, but the appellate court and the Supreme Court thought a different way," Bowman said. "In the midst of all that, he picks up another charge while in prison and now he's facing an adult charge. This is not a situation you encounter every day."

Carter's public defender, Scott Sherman, declined to talk about the case.

After the carjacking case went up in smoke, what remained for Carter was the shank case. It appears that questions about his competency were never raised in that case. After a one-day trial, a six-person jury on Oct. 25 acquitted him, court records show. The jury deliberated for 35 minutes. Attempts to reach jurors Monday were unsuccessful.

Seven days later, amid a packed, costumed crowd, Carter, now 19, fired away, police say. He turned himself in Friday about 1 p.m. after police announced he was their main suspect. NOPD Superintendent Ronal Serpas said numerous Crimestoppers tips and witness accounts contributed to his identification.

Because of the legal wrangling in criminal court, a Juvenile Court judge has yet to revisit Carter's competency to stand trial in the carjacking.

Carter is scheduled to appear in magistrate court on March 4 on a first-degree murder charge in Glover's killing.

Dussett, now 18, is slated to stand trial in the 2009 carjacking on Dec. 5 in Davis' courtroom.